1. Field
The disclosed and claimed concept relates generally to an apparatus and method for weighing and, more particularly, to an apparatus and method for weighing the contents of a container that is carried by a roll-off truck.
2. Related Art
Roll-off trucks and containers are employed in numerous diverse applications. For instance, a container may be deposited by a roll-off truck at a construction site, and refuse from the construction site is gradually placed into the container. The roll-off truck may periodically return to the construction site and remove the container for dumping at another location, after which the empty container may be returned to the construction site. By way of further example, several containers may be located at a recycling facility, with desirable materials such as aluminum, copper, and steel being placed in separate containers for recycling purposes and with refuse materials being placed in another container.
Depending upon the needs of the application, the containers may be removed by a roll-off truck for dumping in various circumstances. For instance, in some circumstances the container may be dumped once it has been filled to a predetermined proportion of its capacity. Alternatively, the container may be removed for dumping according to a periodic schedule regardless of the extent to which the container is filled, by way of example.
As a general matter, it is desirable to ascertain the weight, i.e., mass, of the contents of the container for various purposes. For instance, in a refuse dumping operation, the weight of the contents is typically used as at least one of the criteria in calculating the charges that are to be billed to the person who generated the refuse. In a recycling operation, the weight of the recyclable material in the container is typically used as at least one of the criteria employed in determining the amount that is to be paid to the person who collected the recyclable materials.
While previously known systems for determining the weight of the contents of a container have generally been effective for their intended purposes, they have not been without limitation. For instance, it has been known to provide a scale at a dumping site to determine the weight of the contents of a container by weighing the truck with the container and its contents prior to dumping and by also weighing the truck and the empty container after dumping in order to calculate from the two weight values the weight of the contents that were dumped. However, such scales are expensive to install and are also costly to operate since a person typically must be employed to take and record measurements. Moreover, since a dumping facility typically will have only one such scale, and all of the trucks and their containers must be weighed twice with each dumping operation, i.e., before and after dumping, trucks can sometimes be required to wait in long lines in order for the weighing operations to be performed. Such waiting is wasteful both in terms of labor and truck time, and the fuel that is consumed in such waiting typically is not factored into the net weight that is calculated from the two weighing operations, which leads to inaccuracy.
It has also been known to provide certain weighing systems on the roll-off trucks themselves. In order for such weighing systems to be used for their intended purposes, i.e., for the purposes of making weight measurements of sufficient accuracy that they can be employed in calculating dollar amounts that are to be paid from one person to another, such a weighing system must be “legal for trade”. However, a weighing system that is “legal for trade” typically includes components that are highly sensitive, and a container with its contents may weigh upwards of twenty tons or more. As such, while the load cells or other weight measurement elements must be engaged by the container in order to provide a weight measurement, the container must be disengaged from such load cells prior to transport of the container. This is because load cells of such “legal for trade” accuracy cannot withstand the abuse that would be experienced if the load cells were engaged by a container while the truck is driven on a roadway. While it has also been known to provide on such a truck lifting structures that can raise a container out of engagement with the load cells after a weight measurement has been recorded, such systems have been undesirably costly due to the required robustness and ability to lift weights of twenty tons or more.